There is a problem which exists during the development of power plants in which hydrogen is used as the working fluid, this problem being that hydrogen to one or another degree interacts with almost all of the structural metal materials, diffusing inside them and making them brittle, which may result in catastrophic destruction of the plants.
At present, structural materials which are less sensitive to hydrogen, for example, high-alloy steels and alloys on a nickel base with the structure of a stable austenite, are used in order to protect power plants from the destructive action of hydrogen. The aforesaid materials are very expensive and are not technological to a sufficient degree, which limits the possibility for their utilization.
A method is known for protecting power plants against the destructive action of hydrogen by changing the construction and technology of the process. However, realization of this method requires the input of large material expenditures and results in reduction of the efficiency.
The most promising method is the method for protecting power plants, in which hydrogen is used as the working fluid, against destruction by reducing the diffusion of hydrogen into the structural metal material of the plant (Ju.I. Archakov "Hydrogen Corrosion of Steel," Moscow, Metallurgiya, 1985, p. 161). In the known method, in order to reduce diffusion of hydrogen into the metal, a protective layer is created on the surface of the metal--elements of the construction are plated or lined with metals having a lower hydrogen permeability or barrier layers are created on the surface of the metal which prevent diffusion of hydrogen into the metal. For example, oxide films, carbide and nitride coatings, or protective layers of other metals are applied (copper plating, silver plating, gold plating, etc. are effected).
The barrier coatings are applied by galvanic, ionoplasma, thermal diffusion, etc., methods, which, since they are labor-consuming and complex in technological execution, are not an effective protection, but only weaken and slow down the process of hydrogenation, wherein, in the majority of cases it is not possible to protect the inner cavities of the power plants or joints of the assembly elements, or to completely eliminate characteristic production defects (cuts, incomplete fusions, scaling of coatings, etc.) which are sources of destruction.